Discussion on the timing of mechanical property testing for welded specimens in pressure vessels that require overall heat treatment equipment.
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There is currently a Q345R storage tank; the medium inside it is highly hazardous, and overall annealing treatment is required. Due to the high hazard of the medium, it is necessary to create product test pieces; therefore, the processing procedure is as follows: The test piece is spot-welded to a small section on the edge of the cylinder, and after welding it together with the longitudinal seam of the cylinder, flaw detection is performed. Then the test plate is cut off and set aside, and work begins on welding components such as end caps. Once all the processing steps are completed, the test piece along with the equipment undergoes overall annealing, after which the test piece is taken for mechanical property testing. So the questions are: 1. Does the above process meet the requirements of the manufacturing process? If not, please indicate a reasonable process. 2. If the above process is correct, then if the mechanical property tests of the test specimens fail, should the equipment be deemed unusable? If the equipment is not to be declared unusable, what should be done in that case? Discussion is welcome. If this equipment does not require heat treatment, then taking the specimen off after cutting it serves as a stopping point; once the mechanical property tests on the specimen are successful, the process of welding the end cap can be continued. There should be no problems with this approach, though of course this is just an aside.
Same question: I’m facing the same issue right now, and I’m looking forward to replies from the experts!
The process flow is correct; if effective quality control is applied throughout the manufacturing of the container, especially during welding and heat treatment processes, there should be no problem in the specimens passing the tests. If a test specimen fails, it can be retested; if it fails again, heat treatment usually has to be performed, but this situation generally does not occur.
This post was last edited by 15837357920 on 2016-1-11 10:09. This kind of situation can also occur. I think the process should be like this. Firstly: an appropriate evaluation method must be selected, and the welding process evaluation should include an annealing step. For products with less stringent requirements and for which the manufacturing process is reliable, performance testing can be carried out after overall annealing. For those with strict requirements, performance testing is carried out before annealing after welding to ensure compliance first. First, the simulated annealing process is carried out using test plates to simulate the post-weld heat treatment, and inspections are conducted; only after confirmation of compliance is the actual product annealed for performance testing. Generally, annealing leads to a decrease in strength; if the strength after welding is not above the lower limit of 20 MPa, the risk becomes very high. If the annealing temperature is high, for example, if the equipment is made of heat-resistant steel, a higher annealing temperature will result in an even greater reduction.
Hello, no matter how well welding and other processes are performed, it’s impossible to have absolutely no defects at all. I was wondering what should be done if the test specimens fail to meet the requirements? Your test sample is unqualified; it can be retested. If it fails again, heat treatment usually needs to be performed anew. What is the basis for this? Can a basis be found in relevant standards?
Hello, I think what you say makes some sense: after welding the longitudinal seams of the cylinder, cut off a test piece (which means an additional test piece will have to be made). First, conduct mechanical property tests; once those are successful, assemble and weld the end caps. After that, subject both the test piece and the entire equipment to heat treatment, and only after that carry out further mechanical property tests. This way, the chances of problems occurring are greatly reduced. Although the possibility of problems with the specimen is low, it is not absolutely zero.
It will be troublesome once it happens. If the impact value is low, annealing is still possible; but if the strength is low, there’s nothing to do except carry out normalizing. It’s basically impossible to perform normalizing on the entire equipment. So never let it come to this. How about conducting a simulation test first?
The previous standard definition explained that if it fails the test, heat treatment must be carried out again. But according to official investigations, this situation hardly exists; it’s hard to say about the products of individual companies. I’ve encountered such cases before, and it depends on how things are handled. Theoretically, if the weld is defective, it should be completely removed before welding again; if there are problems with the base material as well, then it should be discarded. Treat individual products separately.